Severe Weather Discussion – 2008-8-4

Severe Weather Discussion for April 7 and 9-10, 2008.Valid: 04/07/2008.

Highlights:

– Active severe weather event is expected for much of Oklahoma through the overnight hours. Primary threats are tornadoes, destructive hail, and damaging winds.

– Significant severe weather event is possible across much of Texas on Wednesday. In Oklahoma an excessive rain event is also likely.

– Chase Status is increased to Level 4.

Discussion:

Little change to prior forecast and reasoning. Many parameters are in-place for an active severe weather for Oklahoma, except moisture. Elevated moisture has been returning to the region the past few hours and the surface appears to be catching up. With the clock at 1pm, 60F dewpoints are close to the Red River. 12z models are in good agreement that southwest Oklahoma is the prime spot for severe weather. Storms are expected to initiate between 5-6pm and increase during the overnight hours. The most significant threat may occur between 7-9pm as the low level jet develops.

Upper system will pass over the area tonight and rapidly move northeast away from the region by Tuesday afternoon. By early Wednesday a large longwave trof will start developing in the western U.S. In response to this feature, deep layer tropical moisture will stream north across the region. A Canadian cold front is still expected across Oklahoma and this will remain place through Wednesday night. Models want to move this boundary north and I have doubts about that issue. I think this is one event where we'll remain the cold sector. This will also lead to widespread excessive rainfall across the region. Models continue to show 3-5 inches for eastern parts of Oklahoma.

12z NAM shows the warm front just south of I-20 and this looks reasonable on Wednesday. Areas to the south will be in the warm sector and face a significant severe weather threat during the afternoon and evening hours. More details on Tuesday.

Probabilities:

Risk area for any part of OK/TX (valid: 04/08 Day 2):

Slight: 100%Moderate: 75%High: 0%

Chase Status:

Level 4 – Heading to Lawton this afternoon.

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